import java.util.Scanner;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: mirac
 * Date: 2025-07-30
 * Time: 22:36
 */
public class Main_1 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String str = scanner.nextLine();
        System.out.println(func(str));
    }

    public static String func(String str) {
        boolean[] booleans = new boolean[127];
        StringBuilder builder = new StringBuilder();
        for (int i = 0; i < str.length(); i++) {
            char ch = str.charAt(i);
            if(booleans[ch] == false) {
                builder.append(ch);
                booleans[ch] = true;
            }
        }
        return builder.toString();
    }
}
